As to conventional technique, a phrase concatenation based speech synthesis method is well known (For example, JP-A H07-210184 (Kokai)). In this technique, speech uttered by persons is divided into speech units (such as a word, a paragraph, or a phrase), and each speech unit is previously stored in a memory. By reading these speech units and concatenating them, a plurality of sentences are output as a speech.
In such speech synthesis method, the same speech units are used several times among a plurality of sentences. Accordingly, in comparison with the case that all sentences to be output are stored as speech, a data quantity to be stored can be reduced.
However, in the above-mentioned speech synthesis method, recorded speech is divided into speech units by a hand operation. Accordingly, speech units having high usage efficiency cannot be created.